Improving the appearance of one or more of a person's anterior teeth has been undertaken previously by adding an aesthetically appearing porcelain veneer to a respective tooth or teeth. By way of example, Thomas S. Greggs, in his U.S. Pat. No. 4,473,353, illustrates and describes his method for cosmetic restoration of anterior teeth. He custom made a glazed porcelain labial veneer for a patient's tooth. Thereafter, he chemically and mechanically bonded the glazed porcelain labial veneer to the respective patient's tooth, to provide a healthful and long lasting cosmetic restoration of desired color, shape, and aesthetic appearance.
More particularly, Thomas S. Greggs, and his assistants, including a lab technician, created and applied the aesthetically appearing porcelain veneer to a respective tooth utilizing a method which he described as follows:
Conventional crown and bridge impression materials were used in taking an impression of the patient's teeth, and recordings were made pertaining to the patient's bite, shade and other pertinent data; PA1 The patient's impression was filled by pouring in die stone materials; PA1 A Pindex model was made, pinning all teeth to be veneered, as well as adjacent teeth; PA1 Each tooth die was undercut at the cervical extension, trimmed at the marginal areas of the regions to be veneered and hardened, so as to replicate the identical structure of the cosmetically defective tooth; PA1 A triangular shaped platinum foil was placed over the labial surface of the tooth die with the apex pointed downward and forming a tab portion which extends below the gingival margin. The base of the triangular shaped foil was folded over the incisal edge of the die and at least partially around the proximal surfaces, in such a manner as to form a snugly fitting, but hingedly removable at the top, foil sheath on the tooth die. For added retention, the foil was adhered to the previously made undercut; PA1 The platinum matrix was removed from the die using the tab portion formed by the foil apex and pulling the foil sheath hingedly off the incisal edge of the die; PA1 The platinum matrix was then held over a Bunsen burner flame to decontaminate it; PA1 The platinum matrix was then reapplied to the die; PA1 Thereafter the platinum matrix was burnished thereon in some way which was not explained; PA1 Porcelain was then applied to the labial surface of the platinum matrix using a brush, starting at the cervical undercut and working up to the incisal edge, and in so doing, the building up of the porcelain was undertaken thinly and uniformly; PA1 The platinum matrix, also called the foil matrix with the porcelain was removed from the tooth die and placed on a tray, then in turn placed in a furnace for firing; PA1 The foil matrix and baked porcelain veneer thereon were then replaced on the tooth die. The marginal areas of the porcelain veneer were finished. Then the porcelain veneer was contoured into an aesthetic shape, and the labial antomy was carved; PA1 The foil matrix and the porcelain veneer were removed from the tooth die for the last time; PA1 The porcelain veneer was cleaned ultrasonically; PA1 Then the porcelain veneer was stained and glazed using conventional techniques to conform to the shade characteristics selected in respect to the patient's teeth; PA1 The room temperature foil matrix and porcelain veneer were placed in distilled water for one minute. Then using tweezers, the foil was gently removed from the porcelain veneer; PA1 The intaglio, or inside surface, of the porcelain veneer was then etched, usually by air abrasion, to promote bonding thereof to the enamel tooth surface; PA1 Then the appropriate enamel surfaces of the patient's tooth were etched with an acid gel formulation, to create micropores and thereby promote bonding; PA1 The intaglio surface of the porcelain veneer was then coated with a thin layer of light curing bonding agent; PA1 A similar layer of the bonding agent was applied to the etched enamel bonding surface of the patient's tooth; PA1 Both of these layers of bonding agent were polymerized by light curing; PA1 A coating of dental filler material was then applied to either the patient's tooth or the intaglio surface of the porcelain veneer; PA1 Then the porcelain veneer was placed onto the patient's tooth; PA1 Excess filler material was trimmed away, and the filler material was polymerized by a second application of light; and PA1 Then the dentist finished the proximal and incisal margins to provide a smooth restoration surface. PA1 A patient meets a dentist to ascertain what might be done to make one or more of her or his front teeth more aesthetically acceptable; PA1 A decision is made that a porcelain veneer is possible, with or without other dental preparations being undertaken, to prepare the tooth to receive a porcelain veneer, or laminate. A full crown, otherwise requiring a total cutdown of a tooth is not required; PA1 An impression is taken of the patient's teeth using any suitable crown and bridge impression material. Polyvinyl silloxane is considered the best material, because two pours are to be undertaken to make duplicate models. PA1 The cut to size platinum foil is quickly positioned on the tooth die and held in place using a thin saran like plastic cover to hold this noble metal foil properly in place and to avoid any subsequent possible contamination of this noble metal foil; PA1 This saran like plastic cover is in turn held in place by wrapping its excess end with dental floss, acting as a string, where it extends over a portion of the dowel pin; PA1 Additional portions of dental floss, i.e. string, are used at this same location to fill in a tapered like volume formed by the sharp angle, that has been created between the shoulder of the front tooth die and the extending dowel pin supporting the front tooth die. This additional tapered dental floss wrapping serves to prevent the otherwise possible breaking of portions of the front tooth die. PA1 The dental floss is unwound or unwrapped to free the thin plastic cover and it is removed; PA1 The platinum foil is inspected to make sure the platinum is completely adapted to the front surface of the front tooth die. If this platinum foil is properly adapted to the front tooth die, then the surface texture of the front tooth die will be evident through observing the surface of the platinum foil; PA1 If desired, before its use or at a later time to insure its dead soft quality, also the platinum foil can be handled with tweezers and placed in a furnace and annealed by reaching a bright red heat temperature. After annealing, the platinum foil, by using tweezers, is placed on the gypsum tooth die; PA1 Then with the platinum foil in place on the tooth die, any possible folds, or ripples, which may be left in the platinum foil, can be hand burnished flat and smooth. Generally, the hand burnishing will warp the platinum foil matrix; PA1 Therefore, the platinum foil and front tooth die are covered and wrapped again using the saran like plastic and dental floss; PA1 Then this arrangement or bundle is returned to the forming machine and accurately formed, i.e. swaged or conformed, during the ten second cycle, and then removed; PA1 Unwrapping and uncovering follows to gain access to the platinum foil also referred to as the platinum foil matrix, which is now totally free from fold lines, and it is removed from the front tooth die. Then the noble metal foil is now ready for the application of a porcelain slurry; PA1 By brushing, a porcelain slurry is applied as a coating over the platinum foil matrix, while leaving a central area clear, i.e. uncovered and referred to as a bald area or bald spot, to later be filled in when compensating for the shrinkage of the porcelain upon firing; PA1 Partial drying of the porcelain slurry is undertaken by using tissue to absorb excess water from the porcelain slurry; PA1 Cutting the partially dried first application of this porcelain slurry using a porcelain knife at spaced locations is also undertaken, so the cut areas or volumes will later be utilized when compensating for the shrinkage of the porcelain during firing; PA1 Firing is undertaken in a furnace of the porcelain slurry coating on the platinum foil matrix, i.e. the noble metal foil matrix; PA1 By brushing again, more porcelain slurry is added to cover the bald central area, to fill in the cut areas, and to cover other areas, and in doing so to complete respective contours, and at this time a lighter shade of porcelain slurry is applied at and along the incisal edge, i.e. biting surface, of the porcelain veneer being created; PA1 Firing is undertaken in a furnace again of the porcelain slurry, the porcelain, and the noble metal foil matrix; PA1 Shaping of the labial, i.e. front, contour of the porcelain follows by using dental tools; PA1 Further characterization, as necessary, is done of the front surfaces of the porcelain to resemble wanted features of the patient's original front tooth surface; PA1 Firing is undertaken in the furnace again of the porcelain coating for a sufficient time to create the wanted glaze of the porcelain; PA1 Removal follows of the platinum foil matrix from the porcelain veneer, also referred to as the porcelain laminate; preferably such removal is done in the presence of water; PA1 Covering the glazed labial surface of the porcelain veneer with a sticky wax is done to protect the glaze of the porcelain; PA1 Roughening the interior surface of the porcelain veneer is done by sandblasting or etching; PA1 Washing the porcelain veneer then removes the sticky wax; PA1 Checking the fitting of the porcelain veneer to the patient's front tooth is done, and if the fit is excellent as expected; then PA1 Cementing the well fitting porcelain veneer to the patient's front tooth is undertaken creating the porcelain laminate in place.
Mr. Thomas S. Greggs in his U.S. Pat. No. 4,473,353 said the foil matrix was burnished over the tooth die, without describing how the burnishing might be done. In this respect of the forming of the foil matrix, in connection with a new technique for constructing a ceramic to metal crown from a metal foil coping, as disclosed in U.S. Pat. Nos. 4,459,112 and 4,492, 579, Messrs. Itzhak Shoker and Aharon E. Whiteman illustrated and described their dental swager, in their U.S. Pat. No. 5,014,532. To adapt a dental foil coping to a die of a tooth to be restored, their dental swager was used. It had a male punch, and a female base support in which the die of the tooth to be restored was mounted with the metal foil coping placed over the tooth die. An insert was located in the male punch for transferring the force applied to the punch to the metal foil coping and the tooth die. The insert was composed of a solid material having an elastic memory. Also a shock absorber, having a putty-like consistency, separated this insert from the male punch.
In further reference to how a foil matrix might be burnished, Messrs. Danny R. Clark and Asami Tanaka, in their U.S. Pat. No. 4,794,774, illustrate and describe their method of preparing a dental restoration. A die, of a prepared patient's tooth requiring a dental restoration, is fitted with a metal foil. Initially, the metal foil is fitted to the tooth die by using standard folding and crimping techniques. However, the close tolerances required are not as yet met. Therefore the metal foil covered tooth die is then placed in a flexible, fluid impermeable sack and the sack is sealed. Then the sealed sack with the metal foil covered tooth die, is placed in the main chamber of an isostatic press. This main chamber is filled with water and a cap is partially threaded into place. A pump is operated to increase the pressure and drive out air through the partially threaded cap gap. When water appears, the cap is tightened and the pressure builds up. Thereafter, the fluid, preferably water, transmits the pressure isostatically against the sealed sack 14 to uniformly press the metal foil against the tooth die. The isostatic pressure is in the range of 1000 to 2500 p.s.i. When the forming is completed, the pressure is released from the system, and the sack 14 is removed from the chamber, and the metal foil covered tooth die is removed from the sack. A superior uniform fit of the metal foil to the tooth die is obtained.
In earlier days in forming gold crowns for teeth, dental swaging apparatus of various types were utilized, as illustrated and described in U.S. Pat. Nos. 582,872 of 1897; 889,085 of 1908; 946,962 of 1910; 1,794,197 of 1931; and 1,883,968 of 1932.
In utilizing hand burnishing methods, oftentimes it becomes very difficult and time consuming to create a good fit between the noble metal foil and the front face of a patient's tooth die. When hand burnishing is being done on one side, then the opposite side of the noble metal foil is affected, often losing its previous good conformance to the tooth die. A compromise fit is then sometimes considered acceptable, yet the final fitting to the patient's tooth may not last for as long a period of time as originally intended.
When attempts are made to form the noble metal foil by using hammer like blows against dies, bearing in turn on the noble metal foil covering a patient's tooth die, quite often the force used is excessive, and the patient's tooth die is destroyed. Such destruction results in the need to create another patient's tooth die causing the unwanted delay and unwanted related cost.
To avoid such difficulties of conforming the noble metal foil by hand burnishing or by excessive hammer like forces, some dental persons use the investment casting method. The patient's tooth die, used in the investment casting method, directly receives the porcelain slurry and therefore it is fired with the porcelain. Considerable time is consumed in preparing the patient's tooth die which must withstand the high firing temperatures. Moreover, when the decision is made that the porcelain veneer is ready for fitting, then this high temperature resistant patient's tooth die is broken away from the porcelain veneer. If the resulting fitting to the patient's front tooth is not considered satisfactory, then a new patient's tooth die must be made, causing an unwanted delay and an unwanted related cost, when this investment casting method has been used.
These inventors and many others have led the way to constantly improve the practice of dentistry. In particular, in reference to the illustrations and descriptions set forth in these patents, their inventions serve to be useful in understanding how today patients' teeth needing cosmetic restoration to gain or to regain their aesthetic appearance, are restored. As always realized, there are still better ways being sought to improve such tooth cosmetic restorations.